The vast majority of internal combustion engines in use at present utilize poppet-type valves. At least in theory, rotary valve-type engines have certain advantages over poppet valve engines, but for some reason or other, rotary valve engines are not in any substantial popular use.
Engines having poppet-type valves are far more complex than those having rotary valves because of the need to associate with the pistons and compression chambers, such additional features as a cam shaft, valve lifters and guides, rocker arms and valve springs; while in contrast, a rotary valve engine requires only a rotatable valve and appropriate seals. The latter elements characteristically have relatively long life and, in general such engines provide increased efficiency in fuel consumption and in addition, usually operate more smoothly and are more quiet in operation than poppet valve-type engines.
Despite the foregoing advantages of rotary valve engines over poppet-type valve engines, it appears that the purchasing public has not adopted the rotary valve-type engines to any appreciable extent. Perhaps this is because manufacturers and repair garages have heavy investment in equipment to manufacture and repair engines having poppet-type valves. Coupled with this is the additional fact that certain problems are characteristic of rotary valve engines, such as adequate sealing, lubrication, tooling and difficulty in repair and maintenance.
Among patents in the prior art, there especially are two which pertain to rotary valve engines that are of interest to the present invention but over which the invention is believed to be patentably distinguishable. These patents are:
U.S. Pat. No. 1,414,692 - Dickerson May 2, 1922 PA1 U.S. Pat. No. 3,945,364 - Cook Mar. 23, 1976 PA1 U.S. Pat. No. 1,746,728 - Ensign Feb. 11, 1930 PA1 U.S. Pat. No. 1,801,367 - Peterson Apr. 21, 1931 PA1 U.S. Pat. No. 1,808,671 - Luyckx June 2, 1931 PA1 U.S. Pat. No. 1,971,060 - Wills Aug. 21, 1934 PA1 U.S. Pat. No. 2,975,774 - Coffey et al Mar. 21, 1961 PA1 U.S. Pat. No. 4,134,381 - Little Jan. 16, 1979
These patents are directed to two-cylce engines, whereas the invention embodies a four-cycle principle for smooth and quiet operation.
There also are additional patents of less interest: